This invention relates a rectifying charge storage element and, more particularly, to electronic circuits fabricated on various substrates, including flexible substrates by various means including printing or other deposition techniques using organic conductors, semiconductors and insulators and other electronic materials suitable for deposition and use in electronic circuits. The invention specifically relates to a power supply that extracts DC power (voltage and current) sufficient to power an electronic device from an AC input signal. The AC input signal may be derived from an inductive, capacitive, or L-C resonant circuit coupled to an external electromagnetic or electrostatic AC field. The electronic circuit thus powered may be a radio frequency identification (RFID) circuit.
Most electronic circuits require a source of DC voltage with sufficient current output to power the circuit elements. Many of these circuits derive DC power by rectifying and filtering an AC power signal Often, the AC signal is provided to the circuitry by electromagnetic coupling.
For example, a passive RFID tag system must be capable of receiving power from an RFID reader to the RFID tag via an inductive (H-field) or electric field (E-field) coupling, and transmitting data from the tag to the reader also via inductive or electric field coupling. Activation field frequency of RFID devices may be from under 100 kHz up to over 30 MHz if inductive or capacitive coupling is utilized, and up to the microwave region if electric field RF antenna coupling is used. In current industry practice, operating power to a passive RFID tag or other electronic circuit is derived by utilizing a rectifier device and a charge-storage device, typically a rectifier diode or combination of diodes connected to a charge storage capacitor or combination of capacitors. In the past, these elements have been implemented as separate components within a discrete circuit or silicon integrated circuit.
Recent advancements in circuitry manufacturing processes, applicable to RFID tags and other similar electronic circuit systems, have enabled the production of electronic circuits on flexible substrates using thin film materials such as organic and polymer semiconductors and other substances that can be applied by techniques such as ink jet printing. A primary objective is to produce electronic devices that have operating characteristics similar to discrete or integrated silicon circuit technology while approaching the economy of printing processes.
Beigel, U.S. Pat. No. 4,333,072 describes an inductively coupled RFID system in which power to an RFID tag is derived from an alternating magnetic field originating in a reader-energizer coupled inductively to the tag antenna, and rectified by a rectifier in the antenna with the resulting DC charge stored in a capacitor in the tag.
Beigel, U.S. Pat. No. 5,973,598 describes an RFID tag formed on a flexible substrate by depositing or printing conductive, semiconductive and insulating substances in an operative pattern on the substrate.
Sturm et al, U.S. Pat. No. 6,087,186 describes the fabrication of electronic circuits on flexible substrates by ink jet printing methods. U.S. Pat. No. 6,037,718 describes an organic transistor stacked on an electroluminescent display element. U.S. Pat. No. 5,915,197 describes a “varicap” diode formed by silicon processes.